Spectral confocal distance measurement system based on scanning galvanometer

Abstract

The present invention provides a spectral confocal distance measurement system based on a scanning galvanometer, comprising: a light source system, a dispersive objective lens and a spectrometer device; the light source system is used to emit a parallel light beam composed of multiple wavelengths, and the parallel light beam is sequentially reflected by a first galvanometer, refracted by a first double telecentric system, reflected by a second galvanometer and refracted by a second double telecentric system, and then incident on a dispersive objective lens to be dispersed, and after forming a dispersive light beam, the object to be measured is irradiated; the reflected light beam with the surface information of the object to be measured emitted by the object to be measured returns along the original path, and finally incident on the spectrometer device to obtain the surface information of the object to be measured; by controlling the rotation speed ratio of the first galvanometer and the second galvanometer, the surface information at different positions of the object to be measured is obtained, and the overall surface morphology of the object to be measured is measured. The present invention realizes an optical system for spectral confocal distance measurement with large range, high precision and high stability.

Description

Technical Field

[0001] The invention relates to the field of optical technology, and in particular to a spectral confocal distance measurement system based on a scanning galvanometer. Background Art

[0002] The traditional measurement method based on spectral confocal ranging is single-point measurement, which can only extract the height information of one point on the sample surface during measurement. The spectral confocal system needs to be equipped with an XY plane or lateral two-dimensional scanning system when measuring the overall surface morphology of the object, resulting in poor system stability. The scanning method based on scanning XY galvanometer can greatly reduce the movement of mechanical parts and improve scanning efficiency, which is of great significance in rapid real-time measurement in industrial sites.

[0003] Confocal microscopy is the most typical method to realize optical tomography microscopy. The earliest confocal microscopy imaging device was proposed by M Minsky, a junior researcher at Harvard University in the United States in the mid-to-late 1950s, in 1961, and obtained the US invention patent. Spectral confocal technology is developed on the basis of confocal microscopy. It is a non-contact measurement method that combines the confocal principle of confocal microscopy and the dispersion focusing principle. At present, spectral confocal technology has a wide impact in modern biology and medicine, physics, chemistry, materials science, nanotechnology, precision measurement and other fields.

[0004] like Figure 1 As shown, the existing solution that is closer to this patent is a line scanning spectral confocal ranging system, which has a light source that includes all visible light bands. After the light emitted by the light source passes through the first slit 01, it will form a line light source in the X-axis direction. The line light source is dispersed on the Y-axis through the first optical component 03, and light beams of different wavelengths will be focused at different heights, thereby forming a confocal plane in the Z-axis direction. Only the light focused on the normal line of the object to be measured will pass through the second optical component 04, the second slit 02 and the third optical component 05, and finally enter the detector. Finally, the spectral data is decoded by image processing to obtain the surface depth information of the object to be measured.

[0005] The outstanding feature of the traditional spectral confocal measurement method is that it uses polychromatic light to disperse and focus on the optical axis through multiple lenses to produce axial continuous focus. This continuous focal shift is used as an encoding method for measuring the sample surface height. The traditional measurement method based on this method is single-point measurement, which can only extract the height information of one point on the sample surface during measurement. When measuring the overall surface morphology of an object, the spectral confocal system needs to be equipped with an XY plane or horizontal two-dimensional scanning system, which is not stable enough, limiting the measurement speed and the application of real-time measurement in industrial sites. Summary of the invention

[0006] In view of the above problems, the purpose of the present invention is to propose a spectral confocal ranging system based on a scanning galvanometer, by applying a high-precision scanning galvanometer to the spectral confocal system and performing super-achromatic aberration and object-image telecentric optical path matching design, thereby realizing a large-range, high-precision, and high-stability spectral confocal ranging optical system.

[0007] To achieve the above object, the present invention adopts the following specific technical solutions:

[0008] The present invention provides a spectral confocal distance measurement system based on a scanning galvanometer, comprising: a light source system, a first galvanometer, a first double telecentric system, a second galvanometer, a second double telecentric system, a dispersive objective lens and a spectrometer device;

[0009] The light source system is used to emit a parallel light beam composed of multiple wavelengths. The parallel light beam is sequentially reflected by the first galvanometer, refracted by the first double telecentric system, reflected by the second galvanometer, and refracted by the second double telecentric system, and then incident on the dispersive objective lens to be dispersed. After the dispersive light beam is formed, the object to be measured is irradiated; the first galvanometer and the second galvanometer rotate along the preset directions respectively;

[0010] The dispersive beams of different wavelengths generated by the dispersive objective lens will be focused at different depths of the object under test along the Z direction; the reflected beam with the surface information of the object under test will return along the original path and finally enter the spectrometer device to obtain the surface information of the object under test;

[0011] By controlling the movement speed of the first galvanometer and the second galvanometer, the surface information at different positions of the object to be measured is obtained, and the measurement of the overall surface morphology of the object to be measured is completed.

[0012] Preferably, the light source system comprises: a light source, a beam splitter and a collimator;

[0013] The light source is used to emit a polychromatic light beam which is incident on the beam splitter. The polychromatic light beam reflected by the beam splitter is incident on the collimator. The collimator collimates the polychromatic light beam into a parallel light beam which is incident on the first galvanometer.

[0014] Preferably, the first dual telecentric system comprises: a first telecentric lens and a second telecentric lens;

[0015] The rear focus of the first telecentric lens coincides with the front focus of the second telecentric lens; the parallel light beam is refracted by the first telecentric lens and converges to the focus of the first telecentric lens, and then is collimated by the second telecentric lens to be a parallel light beam incident on the second galvanometer.

[0016] Preferably, since the optical path is reversible, the parallel light beam entering the second galvanometer is completely identical to the parallel light beam emitted from the first galvanometer.

[0017] Preferably, the second dual telecentric system comprises: a third telecentric lens and a fourth telecentric lens;

[0018] The rear focus of the third telecentric lens coincides with the front focus of the fourth telecentric lens; the parallel light beam is refracted by the third telecentric lens and converges to the focus of the third telecentric lens, and then is collimated by the fourth telecentric lens to be a parallel light beam incident on the dispersive objective lens.

[0019] Preferably, the second dual telecentric system further comprises: a folding mirror;

[0020] The turning mirror is located at the overlapping position of the rear focus of the third telecentric lens and the front focus of the fourth telecentric lens; the turning mirror is used to fold the light path and shorten the length of the optical system.

[0021] Preferably, the first galvanometer performs rotational motion along the X direction, and the parallel light beam is incident on the first double telecentric system after being reflected by the first galvanometer;

[0022] The second galvanometer rotates along the Y direction, and the parallel light beam is incident on the dispersion objective lens after being reflected by the second galvanometer.

[0023] The dispersed beams of different wavelengths produced by the dispersive objective will be focused at different depths of the object being measured along the Z direction;

[0024] The overall surface morphology of the object to be measured is measured by controlling the rotation speed ratio of the first galvanometer and the second galvanometer.

[0025] Preferably, the movement speeds of the first galvanometer and the second galvanometer in the X direction and the Y direction are controlled respectively to match the aspect ratio of the object to be measured.

[0026] Preferably, the spectrometer device comprises: a spectrometer and a pinhole;

[0027] When the object to be measured is fixed, only a dispersed light beam of a certain wavelength will be focused on the surface of the object to be measured, and return along the original optical path, passing through the beam splitter and entering the spectrometer. Light beams of other wavelengths will be blocked by the small hole during the reflection process and cannot enter the spectrometer.

[0028] Compared with the existing technology, the high-precision scanning galvanometer is applied to the spectral confocal system, and the super-apochromat and object-image telecentric optical path matching design are performed to realize a large-range, high-precision, high-stability spectral confocal ranging optical system. The present invention can not only measure the overall surface morphology of the measured object, but also ensure the high stability of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a structural schematic diagram of a line scanning spectral confocal ranging system in the prior art.

[0030] Figure 2 It is a structural schematic diagram of a spectral confocal ranging system based on a scanning galvanometer provided in an embodiment of the present invention.

[0031] Figure 3 It is a flow chart of a spectral confocal ranging system based on a scanning galvanometer provided in an embodiment of the present invention.

[0032] Figure 4 It is a schematic diagram of the optical path of a spectral confocal ranging system based on a scanning galvanometer provided in an embodiment of the present invention.

[0033] Figure 5 It is a schematic diagram of the working principle of the galvanometer of the spectral confocal ranging system based on the scanning galvanometer provided in an embodiment of the present invention.

[0034] The reference numerals include: a first slit 01, a second slit 02, a first optical component 03, a second optical component 04 and a fifth optical component 05;

[0035] Spectrometer 1, pinhole 2, light source 3, beam splitter 4, collimator 5, first galvanometer 6, first telecentric lens 7, second telecentric lens 8, second galvanometer 9, third telecentric lens 10, folding mirror 11, fourth telecentric lens 12, dispersive objective lens 13 and object to be measured 14. DETAILED DESCRIPTION

[0036] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the following description, the same modules are represented by the same reference numerals. In the case of the same reference numerals, their names and functions are also the same. Therefore, the detailed description thereof will not be repeated.

[0037] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and do not constitute a limitation of the present invention.

[0038] Figure 2 The schematic diagram of the structure of the spectral confocal distance measurement system based on the scanning galvanometer provided in the embodiment of the present invention is shown.

[0039] Figure 3 The figure shows a flow chart of a spectral confocal distance measurement system based on a scanning galvanometer provided in an embodiment of the present invention.

[0040] Figure 4 The optical path schematic diagram of the spectral confocal distance measurement system based on the scanning galvanometer provided in an embodiment of the present invention is shown.

[0041] like Figure 2-4 As shown, the spectral confocal ranging system based on scanning galvanometer provided in an embodiment of the present invention includes: a light source system, a first galvanometer 6, a first double telecentric system, a second galvanometer 9, a second double telecentric system, a dispersive objective lens 13 and a spectrometer device.

[0042] The light source system includes: a light source 3 , a beam splitter 4 and a collimator 5 .

[0043] The light source 3 is used to emit a multi-color light beam which is incident on the beam splitter 4 . The light beam reflected by the beam splitter 4 is incident on the collimator 5 . The collimator 5 collimates the multi-color light beam into a parallel light beam which is incident on the first galvanometer 6 .

[0044] The first galvanometer mirror 6 can rotate along the X direction, and the parallel light beam is incident on the first double telecentric system after being reflected by the first galvanometer mirror 6 .

[0045] The first double telecentric system includes: a first telecentric lens 7 and a second telecentric lens 8. The back focus of the first telecentric lens 7 coincides with the front focus of the second telecentric lens 8.

[0046] The parallel light beam is refracted by the first telecentric lens 7 and becomes a convergent light beam, which converges to the focus of the first telecentric lens 7 , and then is collimated by the second telecentric lens 8 to become a parallel light beam and incident on the second galvanometer 9 .

[0047] Since the optical path is reversible, the parallel light beam entering the second galvanometer mirror 9 has the same properties as the parallel light beam emitted from the first galvanometer mirror 6, thereby ensuring aperture matching.

[0048] The second galvanometer mirror 9 can rotate along the Y direction. After being reflected by the second galvanometer mirror 9, the parallel light beam is incident on the second double telecentric system.

[0049] The second double telecentric system includes: a third telecentric lens 10 , a folding mirror 11 and a fourth telecentric lens 12 .

[0050] The deflection mirror 11 is used to deflect the light path and shorten the length of the optical system. The deflection mirror 11 is located at the overlapping position of the rear focus of the third telecentric lens 10 and the front focus of the fourth telecentric lens 12.

[0051] The parallel light beam is refracted by the third telecentric lens 10, reflected by the deflection mirror 11 and refracted by the fourth telecentric lens 12, and then incident on the dispersive objective lens 13. The dispersive objective lens 13 irradiates the object to be measured 14 after the parallel light beam is dispersed. The scattered light beam emitted by the object to be measured 14 returns along the original path, passes through the dispersive objective lens 13, the second double telecentric system, the second galvanometer 9, the first double telecentric system and the first galvanometer 6, and is incident on the spectrometer device.

[0052] Light of different wavelengths is focused at different depths, and only the light beam of the wavelength focused on the surface of the object 14 can be reflected back to the original path and incident on the spectrometer device.

[0053] The spectrometer device comprises: a spectrometer 1 and a pinhole 2.

[0054] The light beams of different wavelengths generated by the dispersive objective lens 13 will be focused at different depths in the Z direction of the object 14. When the object 14 is fixed, only light of a certain wavelength will be focused on the surface of the object and return along the optical path, passing through the beam splitter and entering the spectrometer 1, while light of other wavelengths will be blocked by the pinhole 2 during the reflection process and cannot enter the spectrometer 1.

[0055] Figure 5 The schematic diagram shows the working principle of the galvanometer of the spectral confocal ranging system based on the scanning galvanometer provided in an embodiment of the present invention.

[0056] like Figure 5 As shown, by controlling the movement speed of the first galvanometer 6 and the second galvanometer 9 in the x-direction and the y-direction, the overall surface morphology of the object 14 can be measured.

[0057] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

[0058] The above specific implementations of the present invention do not constitute a limitation on the protection scope of the present invention. Any other corresponding changes and modifications made based on the technical concept of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A spectral confocal ranging system based on a scanning galvanometer, characterized in that: include: A light source system, a first galvanometer, a first double telecentric system, a second galvanometer, a second double telecentric system, a dispersive objective lens and a spectrometer device; The light source system is used to emit a parallel light beam composed of multiple wavelengths, and the parallel light beam is sequentially reflected by the first galvanometer, refracted by the first double telecentric system, reflected by the second galvanometer, and refracted by the second double telecentric system, and then incident on the dispersive objective lens to be dispersed, and the dispersed light beam is formed to irradiate the object to be measured; the first galvanometer and the second galvanometer respectively rotate along the preset directions; The dispersion objective lens generates dispersion light beams of different wavelengths which are focused at different depths of the object to be measured along the Z direction; the reflected light beam emitted by the object to be measured and carrying the surface information of the object to be measured returns along the original path and finally enters the spectrometer device to obtain the surface information of the object to be measured; By controlling the movement speeds of the first galvanometer and the second galvanometer, the surface information at different positions of the object to be measured is obtained, thereby completing the measurement of the overall surface morphology of the object to be measured.

2. The spectral confocal ranging system based on scanning galvanometer according to claim 1, characterized in that: The light source system comprises: a light source, a beam splitter and a collimator; The light source is used to emit a polychromatic light beam which is incident on the beam splitter. The polychromatic light beam reflected by the beam splitter is incident on the collimator. The collimator collimates the polychromatic light beam into a parallel light beam which is incident on the first galvanometer.

3. The spectral confocal ranging system based on scanning galvanometer according to claim 2, characterized in that: The first dual telecentric system comprises: a first telecentric lens and a second telecentric lens; The rear focus of the first telecentric lens coincides with the front focus of the second telecentric lens; the parallel light beam is refracted by the first telecentric lens and converges to the focus of the first telecentric lens, and then is collimated by the second telecentric lens to be a parallel light beam incident on the second galvanometer.

4. The spectral confocal ranging system based on scanning galvanometer according to claim 3, characterized in that: Since the optical path is reversible, the parallel light beam entering the second galvanometer is completely the same as the parallel light beam emitted from the first galvanometer.

5. The spectral confocal ranging system based on scanning galvanometer according to claim 4, characterized in that: The second double telecentric system comprises: a third telecentric lens and a fourth telecentric lens; The rear focus of the third telecentric lens coincides with the front focus of the fourth telecentric lens; the parallel light beam is refracted by the third telecentric lens and converges to the focus of the third telecentric lens, and then is collimated by the fourth telecentric lens to be a parallel light beam incident on the dispersive objective lens.

6. The spectral confocal ranging system based on scanning galvanometer according to claim 5, characterized in that: The second double telecentric system further comprises: a folding mirror; The folding mirror is located at the overlapping position of the rear focus of the third telecentric lens and the front focus of the fourth telecentric lens; the folding mirror is used to fold the light path and shorten the length of the optical system.

7. The spectral confocal ranging system based on scanning galvanometer according to claim 6, characterized in that: The first galvanometer performs rotational motion along the X direction, and the parallel light beam is incident on the first double telecentric system after being reflected by the first galvanometer; The second galvanometer performs rotational motion along the Y direction, and the parallel light beam is incident on the dispersive objective lens after being reflected by the second galvanometer; The dispersion objective lens generates dispersion light beams of different wavelengths which are focused at different depths of the object to be measured along the Z direction; The measurement of the overall surface morphology of the object to be measured is completed by controlling the rotation speed ratio of the first galvanometer and the second galvanometer.

8. The spectral confocal ranging system based on scanning galvanometer according to claim 7, characterized in that: The movement speeds of the first galvanometer and the second galvanometer in the X direction and the Y direction are controlled respectively to match the aspect ratio of the object to be measured.

9. The spectral confocal ranging system based on scanning galvanometer according to claim 8, characterized in that: The spectrometer device comprises: a spectrometer and a pinhole; When the object to be measured is fixed, only a dispersed light beam of a certain wavelength will be focused on the surface of the object to be measured, and return along the original optical path, passing through the beam splitter and incident on the spectrometer. Light beams of other wavelengths will be blocked by the small hole during the reflection process and cannot enter the spectrometer.

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